Issue connecting to aws rds instance

We are accessing AWS RDS and EC2 instances through an EC2 Bastion instance. We have 2 issues that I think are related:
Access to AWS in general is sluggish even though my internet shows 87.8 mbps download and 22.2 upload.
The other issue is that we get the following error when accessing an RDS server using Python’s sqlalchemy library:
(pymysql.err.InternalError) Packet sequence number wrong - got 1 expected 0

I’ve tried it from 5 different wifi locations. In some cases every sql query fails but in on instance, an iPhone hotspot, it worked fine. So I suspect it might also be a performance issue.

How can I fix this issue?